about a year ago I posted here asking for the Spectre x360 13-ac000 touchscreen firmware.
Here's my old post:
There were several people who had the same problem. I can't post there because the topic is archived. I have good news! :)
HP has finally sent me the original firmware for my device! Well, they sent me 3 and 1 of them worked.
If anyone still has the same problem, you can get the firmwares they sent me from here:
https://drive.google.com/open?id=1w_DFDUazum6Pu_oLk6kW69Xi6UfY3AJd
The one that worked for me is Sphinx2.0 (FHD). After the install, I needed to reboot my computer for the touchscreen to work properly again. This did NOT fix the pen/touch delay issue but it fixed the bricked screen.
These are FIRMWARES! so, install at your own risk!